Table 1. Main characteristics of studies included in the systematic review and meta-analysis.
| Author; year of Publication (reference) |
Design, Period (Country) |
Subjects source | Test(s) done | Number screened | RVF +ve after screening N (%) | Enrolled N (%) | Age (years) | Main study aim |
|---|---|---|---|---|---|---|---|---|
| Adam; 2010[31] | Cross-sectional, Sep–Nov 2007 (Sudan) |
In-patients | ELISA IgM | 18 | 18 (100%) | 18 M: 15(83%) F: 3(17%) |
Mean: 38.7(sd: 14.4) Median: missing |
Describe the manifestations, morbidity, and mortality related to the recent outbreak of RVF in central Sudan. |
| El Imam; 2009[32] | Cohort, Sep 2007—Jan 2008 (Sudan) |
In-patients | Not mentioned | 392 | Missing | 194 M: 145(73%) F: 49(25%) |
Mean: 34(sd: missing) Median: missing (range: 15–65) |
Estimate the incidence of renal impairment, the demographics and modes of presentation as well as to determine the mortality rate related to renal impairment in patients with RVF |
| Baudin; 2016[33] | Cross-sectional, Jun–Nov 2012 (Sudan) |
In-patients | ELISA IgM PRNT rtPCR |
130 | 28 (22%) | 28 M: 0(0%) F: 28(100%) |
Mean: 27.8(sd: 5.0) Median: missing(range: 17–37) |
Determine which infectious agents were the cause of miscarriage in a cross-sectional study of febrile pregnant women who attended a hospital in Port Sudan, Sudan |
| Smithburn; 1949[34] | Case series, Dec 1944 –Apr 1948 (Uganda) |
In-patients & out-patients/ laboratory workers | VNT MI&H MPT |
8 | 8 (100%) | 8 M: 8(100%) F: 0(0%) |
Mean: 30(sd: 8.5) Median: 27(range: 22–45) |
Report these cases, together with certain incidental observations of significance |
| Henderson; 1972[35] | Cohort, April–May 1968 (Uganda) |
In-patients & out-patients | CF VNT |
7 | 7 (100%) | 7 M: 6(86%) F: 1(14%) |
Mean: 28(sd: 5.7) Median: 28(range: 19–35) |
Investigate the natural hosts and vectors of Rift Valley fever (RVF) virus during April and May 1968 outbreak affecting seven cases among persons living at Nakiwogo, Bunono and Lunyo on the outskirts of Entebbe near the East African Virus Research Institute (EAVRI) in Uganda |
| St. Maurice; 2016 & 2018[36,37] | Case series, Mar–Jun 2016 (Uganda) |
In-patients | ELISA IgM rtPCR |
3 | 3 (100%) | 3 M: 3(100%) F: 0(0%) |
Mean: missing Median: missing (range: 16–45) |
Examine the physiologic consequences of RVFV infection in the human host using blood samples collected serially as part of clinical care. |
| Nguku; 2010[20] | Cross-sectional, Nov 2006 –Mar 2007 (Kenya) |
Community patients | ELISA IgM rt-PCR |
970 | 121 (12%) | 121 M: missing F: missing |
Mean: missing Median: missing (range: 2–85) |
Describes the magnitude and geographic scope of the outbreak and characterize epidemiologic, ecologic, and virologic features of the epidemic in Kenya |
| Kahlon; 2010[17] | Case series, Dec 2006 –Feb 2007 (Kenya) |
In-patients & out-patients | ELISA IgM rtPCR |
15 | 6 (40%) | 6 M: 3(50%) F: 3(50%) |
Mean: 31(sd: 11.1) Median: 25(range: 24–50) |
Assess and fully evaluate both the early and late clinical course of acutely ill RVF patients |
| Anyangu; 2010[38] | Cross-sectional, Jan–Mar 2007 (Kenya) |
Community patients | ELISA IgM rtPCR |
861 | 202 (23%) | 202 M: missing F: missing |
Mean: missing Median: missing |
Determine risk factors associated with RVF infection, severe illness, and death |
| Abdel-Wahab; 1978[39] | Case series, Oct–Dec 1977 (Egypt) |
In-patients & out-patients | CF VNT Histopathology |
13 | 13 (100%) | 13 M: 13(100%) F: 0(0%) |
Mean: missing Median: missing(range: 25–28) |
Study several cases of infection, which occurred in Inshas, near Belbes, as well as two patients, admitted to Abbassia Fever Hospital in Cairo. |
| Laughlin; 1979[40] and Siam; 1980[41] | Case series, Oct–Dec 1977 (Egypt) |
In-patients | HAI MNT |
Missing | 22 (100%) | 22 M: 13(59%) F: 9(41%) |
Mean: missing Median: missing(range: 5–52) |
Report the clinical spectrum of human disease observed during the recent epidemic. |
| Madani; 2003[5] | Cohort, Aug 2000 –Sep 2001 (Saudi Arabia) |
In-patients | ELISA IgM, rtPCR IHC |
834 | 683 (82%) | 683 M: 565(83%) F: 118(17%) |
Mean: 46.9(sd: 19.4) Median: 50(range: 10–90) |
Study summarizes the epidemiological, clinical, and laboratory characteristics of this first confirmed occurrence of RVF outside Africa. |
| Mohammed Al-Hazmi; 2003[21] | Cohort, Sep–Nov 2000 (Saudi Arabia) |
In-patients | ELISA IgM ELISA IgG rtPCR Virologic typing |
165 | 165 (100%) | 165 M: 136(82%) F: 29(18%) |
Mean: 47.5(sd: missing) Median: 50(range: 15–95) |
Determine the clinical pattern of RVF, the frequency of its complications, and the associated case-fatality rates among patients in Saudi Arabia. |
| Ali Al-Hazmi; 2005[42] | Cross-sectional, Sep–Nov 2000 (Saudi Arabia) |
In-patients & out-patients | ELISA IgM ELISA IgG |
329 | 319 (97%) | 143 M: 111(78%) F:32(22%) |
Mean: 53.2(sd: missing) Median: missing(range: 14–80) |
Determine the clinical pattern of ocular manifestations of RVF and to determine the outcome of ocular lesions during the follow-up period. |
| Kahiry; 2005[43] | Cohort, Sep–Dec 2000 (Yemen) |
In-patients & out-patients | ELISA IgM | 143 | 48 (34%) | 48 M: 25(52%) F: 23(48%) |
Mean: 37.8(sd: missing) Median: missing(range: 8–70) |
Study the epidemiological and clinical pattern of positive RVF cases in Al-Zuhrah district—Hodiedah Governorate at the time of RVF epidemic in Yemen Sep—Dec 2000. |
| Swanepoel; 1979[44] | Case series, Feb–Jun 1977 (Zimbabwe) |
In-patients & Out-patients | ID EM HAI |
45 | 43 (96%) | 43 M: missing F: missing |
Mean: missing Median: missing |
Report the occurrence of encephalitis, ocular complications and fatal haemorrhagic fever in Rhodesia |
| Lagare; 2019[45] | Cross-sectional, Aug–Dec 2016 (Niger) |
Community patients | ELISA IgM rt-PCR |
399 | 17 (4%) | 17 M: 6(35%) F: 11(65%) |
Mean: 23(sd: missing) Median: missing(range: 3–70) |
Describe the outbreak and report the results of serological and molecular investigations of human and animal samples collected. |
| Joubert; 1951[46] | Case series; Mar–May 1951 (South Africa) |
Community patients | CF VNT |
33 | 23 (70%) | 23 M: missing F: missing |
Mean: missing Median: missing |
Investigation of this outbreak of Rift Valley fever was undertaken in the Bultfontein district of the Western Orange Free State. |
| Shrire; 1951[47] | Case series, Mar–Jun 1951 (South Africa) |
Out-patients/ farm workers | Serology | 6 | 6 (100%) | 6 M: 6(100%) F: 0(0%) |
Mean: 36(sd: 8.2) Median: 34(range: 28–50) |
Describe five cases of macular exudates and one case of retinal detachment recently seen in my practice. All of these have been proved serologically. |
| Mundel; 1951[48] | Case series, April 1951 (South Africa) |
Out-patients/ farm workers & veterinarians | MPT CF |
7 | 5 (71%) | 5 M: 5(100%) F: 0(0%) |
Mean: 41(sd: 13.4) Median: 35(range: 32–64) |
Record an outbreak of human Rift Valley fever which originated at the farm Rietvlei, 10 miles south of the centre of Johannesburg |
| Van Velden; 1977[49] | Cross-sectional, Mar—May 1975 (South Africa) |
In-patients | MI&H CF HAI EM |
Missing | 17 | 17 M: 12(71%) F: 5(29%) |
Mean: missing Median: missing (range: 10–77) |
Investigate the cause of relatively severe illness among 17 patients admitted to hospital in Bloemfontein |
| Archer; 2011[50] | Cross-sectional, Feb–Mar 2008 (South Africa) |
In-patients & outpatients | ELISA IgM rtPCR ISA Virus isolation |
53 | 8 (15%) | 8 M: 5(63%) F: 3(37%) |
Mean: Missing Median: missing(range: 20–29) |
Report the subsequent outbreak of RVF in dairy farmers and farm workers, and the staff and students of a veterinary school. Investigated the prevalence of RVFV infection among them, their clinical presentation, and the risk factors associated with infection. |
| Jouan; 1988[51] | Cross-sectional, Oct 1987 (Mauritania) |
In-patients & outpatients | ELISA IgM Virus isolation |
Missing | 284 | 284 M: missing F: missing |
Mean: missing Median: missing |
Study the prevalence of recent infection and disease among Rosso residents. |
| Faye; 2007[52] | Case series, Sep–Dec 2003 (Mauritania) |
In-patients & community patients | ELISA IgM Virus isolation (phylogenetics) |
98 | 17 (17%) | 17 M: missing F: missing |
Mean: missing Median: 21(range: 7–50) |
Describe the results of a multidisciplinary investigation to determine the extent of outbreak and the key factors responsible for RVFV re-emergence in Mauritania. |
| Sow & Faye; 2014[53] | Cross-sectional, Sep–Nov 2012 (Mauritania) |
Community patients | ELISA IgM ELISA IgG rtPCR |
288 | 41 (14%) | 41 M: 18(44%) F: 23(56%) |
Mean: missing Median: 24(range: 2–86) |
Report the results of RVF investigation and laboratory findings from the 2012 RVF outbreak in Mauritania. |
| Boushab; 2016[22] | Cross-sectional, Sep–Nov 2015 (Mauritania) |
In-patients | ELISA IgM rtPCR |
57 | 31 (54%) | 31 M: 23(74%) F: 8(26%) |
Mean: 25(sd: missing) Median: missing (range: 4–70) |
Describe severe clinical signs and symptoms of Rift Valley Fever in southern Mauritania. |
| Gonzalez; 1987[54] | Case series, 1971–1986 (Central African Republic) |
Out-patients | Fluorescent antibody test | 3471 | 20 (0.6%) | 9 M: missing F: missing |
Mean: missing Median: missing |
The incidence of RVF, as determined by surveys of suspected human arboviral infections in the Central African Republic (CAR). |
| Sow; 2016[55] | Cross-sectional, Sep 2013 –Feb 2014 (Senegal) |
In-patients | ELISA IgM rtPCR |
535 | 11 (2%) | 11 M: 7(64%) F: 4(36%) |
Mean: missing Median: 23(range: 13–32) |
Report multidisciplinary field investigations and laboratory findings in 3 regions of Senegal: Mbour, Linguere, and Kedougou. |
| Kitchen; 1934[9] | Case series, Feb–Oct 1933 (USA) |
Out-patients/ laboratory workers | VNT MI&H |
3 | 3 (100%) | 3 M: 3(100%) F: 0(0%) |
Mean: 28(sd: 7.8) Median: 24(range: 23–37) |
The primary object of this report is to place on record three instances of accidental infection, contracted in the laboratory, with the virus of Rift Valley fever. |
| Francis; 1935[8] | Case series, Oct–Dec 1934 (USA) |
In-patients & outpatients/ laboratory workers | MI&H | 3 | 3 (100%) | 3 M: 3(100%) F: 0(0%) |
Mean: missing Median: missing |
Report deals with three cases of laboratory infection with Rift Valley fever in human individuals, in the first of which the source of the infection is obscure. |
CF, Complement fixation test; ELISA IgG, Enzyme linked immunosorbent Assay Immunoglobulin G; ELISA IgM, Enzyme linked immunosorbent Assay Immunoglobulin M; EM, Electron microscopy; F, Female; HAI, Haemaglutination inhibition test; ID, Agar gel immune diffusion tests; IHC, Immunohistochemistry of biopsy specimens; ISA, loop-mediated isothermal amplification assay; M, Male; MI&H, Mice inoculation & histological exam; MNT, Mouse neutralisation test; MPT, Mice protection test; N, Number; PRNT, Plaque reduction neutralisation test; rtPCR, real time reverse transcriptase Polymerase chain reaction; RVFV, Rift Valley fever virus; sd, standard deviation; USA, United States of America; VNT, Virus neutralisation test; %, Percentage; In-patients, subjects source in the study was hospital based patients requiring admission; Out-patients, subjects source in the study was hospital based patients requiring no admission; In-patients and Out-patients, subjects source in the study was both hospital based patients requiring admission and no admission and data collection in the included studies was combined; Community patients, subjects source in the study was non-hospital based patients found in the community or at home.